Histone deacetylase inhibitors such as sodium butyrate and trichostatin A induce apoptosis through an increase of the bcl-2-related protein Bad

The effects of sodium butyrate (SB) and trichostatin A (TSA) on cell proliferation andapoptosis against human glioma T98G, U251MG, and U877MG cells were investigated. Upon exposure to either SB or TSA, cell proliferation was reduced, and apoptosis detected by DNA fragmentation analysis and the cleavage of CPP32 was induced. Previously, we reported that SB increased the expression levels of p21 (WAF-1) and inhibited G1-S transition of the cell cycle. In this study, we showed that TSA also increased p21 expression, suggesting that histone deacetylase (HDAC) inhibitors may up-regulate p21 protein in common and thus arrest proliferation in the G1 phase of the cell cycle. To further determine the underlying molecular mechanisms of apoptosis with either SB or TSA treatment, we studied the expression levels of apoptosis-related proteins in human glioma cells. SB increased the expression of the Bad protein, although the expression of Bcl-2, Bcl-xL, Bax, and Fas was not changed by theaddition of SB. TSA treatment also up-regulated the expression of Bad protein. The results suggest that HDAC inhibitors such as SB and TSA induce apoptosis through an increase in Bad protein in human glioma cells in vitro.

[Induction of apoptosis through NGF/p75NTR in human glioma cells treated with propentofylline]

Propentofylline (PPF) is a xanthine derivative and it has been reported that PPF stimulated the synthesis/secretion of nerve growth factor (NGF) by cultured astroglial cells. We have reported that PPF induced apoptosis in human glioma cells and as its mechanism, up-regulation of NGF, Fas, Bax beta and down-regulation of Bcl-2 were assumed. Recent studies demonstrated the presence of apoptosis induced via NGF/p75NTR in developmental neuron, oligodendroglia. In the present study, to examine whether signal cascade via NGF/p75NTR participates the apoptosis in human glioma cells treated with PPF, we investigated the immunohistochemical study using anti-mouse monoclonal antibody, immunoprecipitation and northern blot analysis for p75NTR, NF-kappa B in human glioma cells (U251MG, T98G, U87) treated with PPF. We observed the up-regulation of p75NTR, translocation of NF-kappa B to the nucleus after treatment with PPF in these cell lines. According to above results, it is assumed that apoptosis in human glioma cells treated with PPF was induced via NGF/p75NTR.

[Neural protective agents, propentofylline (PPF) could induce apoptotic cell death in the human glioma cells: analysis of Bcl-2 and Bax alpha/Bax beta expressions]

In the previous study, we have shown that propentofylline (PPF) could induce the cellular differentiation and apoptosis-related growth regression in the human glioma cell lines. Its biological functions were partly due to the increasing endogeneous NGF and its high affinity receptor, trk A productions. Although little has been known about the precise machinary regulating the propentofylline induced apoptosis. Recently, we have found that propentofylline could modulate some apoptosis related genes products in the glioma cell lines, i.e. NGF, trk A mRNA levels and Fas protein expressions were increased, whereas bcl-2 mRNA level was decreased. In the present study, we examined the apoptotic signal cascade, especially focusing on the expressing pattern of Bcl-2/Bax gene products. In the normal human astrocyte cells, Bax-beta was markedly expressed, whereas Bcl-2 and Bax-alpha proteins and mRNA were weakly or even nondetectable. Accordingly, Bax beta might be a dominant variant in the normal glial cells, which could have the appropriate balance of proapoptotic (Bax beta) and anti-apoptotic proteins (Bcl-2). In the glioma cells, we showed the over-expressions of Bcl-2 and Bax alpha compared with the normal counterparts. According to Bax dominant theory, Bax, not Bcl-2 may have a major role in regulating apoptosis by means of homodimerization. In might be implied that in the glioma cells, excessive expressions of Bcl-2 and Bax alpha would favor the formation of the Bax alpha/Bax beta heterodimer or the Bax beta/Bcl-2 heterodimer rather than the Bax beta/Bax beta homodimer, which might be presumed to be functional proteins. And finally the increasing relative ratio of Bax alpha/ Bax beta or Bax beta/Bcl-2 to Bax beta/Bax beta could allow the tumor cells to survive. Thus over-expression of the bcl-2 and bax alpha gene renders the glioma cells resistant to apoptosis. In the present study, PPF could promote Bax beta over-expression and Bcl-2 retardative expression in the glioma cells, whereas had no effect on Bax alpha expression. Therefore, PPF might promote apoptotic cell death through the mechanism that restore the glioma cells to the appropriate balance of proapoptotic and anti-apoptotic proteins like as normal astrocytes. Our results indicated that propentofylline might have a potential role as apoptotic modulators in the human glioma cell lines, not only its protective activities against neuronal ischemic damages.

[Expression of HGF and c-met/HGF receptor mRNA in brains of normal rats and in phaeochromocytoma cells PC-12 of rats treated with NGF]

Gene expression of HGF and c-met proto-oncogene was examined during rat brain development and in cultured PC-12 cells, using reverse-transcriptase (RT)-polymerase chain reaction (PCR) technique. The both mRNAs of HGF and c-met proto-oncogene were remained at low levels in the middle and late stages of gestation (E-13 and E-18). After birth, and the level of both mRNA expression suddenly increased. During P-1 and P-12, their high level of expression continued and then decreased in P-20 and adult brain. Both HGF mRNA and c-met photo-oncogene mRNA were transiently expressed between day 2 and day 5, and disappeared in cultured PC-12 cells treated with NGF. The neurites of PC-12 cells that were treated with anti-sense oligonucleotides of HGF and c-met proto-oncogene, were shorter and fewer in number than untreated control cells. We conclude that neurite extension of PC-12 cells treated with NGF may ensue by way of c-MET protein activation and signal transduction pathways. Thus, c-MET protein activation and up-regulation of the two mRNAs may also play an important role in neuronal maturation in the developing rat brain.

[Up-regulation of NGF, trkA, Fas, down-regulation of bcl-2, and induction of apoptosis by propentofylline in human glioma cell lines]

Propentofylline (PPF) has been reported to stimulate the synthesis/secretion of nerve growth factor (NGF) by cultured mouse astroglial cells. In the present study, we examined whether PPF stimulates NGF synthesis in human glioma cell lines, the same as in mouse astroglial cells, and if so, whether NGF has a biological effect on glioma cells. After administration of PPF into the glioma cell lines, we investigated morphological changes and gene and protein expression of NGF, trkA, Fas and bcl-2 by using GFAP staining. Western blotting, and RT-PCR. Glioma cells showed definite morphological changes, including expansion of astrocytic processes, cytoplasmic enlargement and increases in GFAP staining. Interestingly, apoptosis was identified by DNA ladder formation in each of the cell lines. The mRNA and protein expression of NGF, trkA and Fas increased, but expression of bcl-2 decreased. These findings suggest that PPF works as a transcriptional modulator and induces apoptosis in glioma cells.

[Two cases of thrombosis of an aneurysm in the acute stage]

Thrombus formation within aneurysm is common and has generally been proved to be a slowly progressive phenomenon. We report two cases of acute completely thrombosis of aneurysms. The initial angiogram failed to reveal aneurysm and other etiology of subarachnoid hemorrhage. CT revealed diffuse cisternal blood and acute hydrocephalus. We decided to operate on these patients in the acute stage because of the generally-known strict correlation between the amount of cisternal high density on CT and the subsequent development of vasospasm and ischemic event. Case 1. A 68 year-old female was admitted on Day 1 with neurological deterioration of Grade 3 (H & K). Complete angiographic study was done, including the basal view and stereotechnique, but failed to reveal aneurysm. On Day 2 we operated on this patient and discovered a thrombosed aneurysm of the anterior communicating artery (3 X 7 mm in size). Case 2. A 51 year-old male suffering from subarachnoid hemorrhage was transferred to our hospital on Day 0. Emergency angiography gave no information, but the pattern of cisternal clots on CT was suggested the existence of an aneurysm of the right internal carotid artery. The next day we performed angiography once more, at that time 2 X 5 mm internal carotid bifurcated aneurysm was revealed. Shortly thereafter we operated and found the intra-aneurysmal clot. Through consideration of these we have reached the following conclusions. When CT findings in a patient with subarachnoid hemorrhage show the diffuse cisternal clots due to rupture of aneurysm, we should consider immediate surgery even if the angiogram is negative in order to lessen the risk of delayed vasospasm.(ABSTRACT TRUNCATED AT 250 WORDS)